Internal combustion (IC) engines are used throughout the world and mainly for motor vehicles. IC engines account for one of the largest consumers of petroleum products known. Due to the large amount of petroleum products consumed by IC engines and the gases exhausted from IC engines, numerous regulatory agencies have implemented regulations or are in the process of implementing regulations that require minimum average fuel economy of vehicles as well as limit the amount of pollutants that are exhausted from vehicles.
Earlier attempts at reducing vehicle emissions have centered on exhaust gas treatments. For example, earlier attempts have introduced reagents into the exhaust gas stream prior to the gas passing through a catalyst in order to effect selective catalytic reduction (SCR) of the nitrogen oxides (NOx) in the exhaust gases. Additionally, many vehicles now include exhaust gas recirculation (EGR) systems to recirculate at least some of the exhaust gases. Although EGR reduces the harmful emissions of vehicles, it also often reduces the vehicle's fuel economy.
The uses of SCR and EGR have been effective in reducing the emission problems in the exhaust stream, but have done little in improving the fuel economy and fuel consumption of vehicles. With the tighter regulations that are being implemented, many manufacturers have turned their focus to increasing the fuel economy of IC engines. It is generally known that only about thirty to forty percent of the energy produced by the fuel combustion of IC engines translates to mechanical power. Much of the remaining energy is lost in the form of heat. Therefore, one particular area of focus in the motor vehicle industry has been to recover some of the heat that is generated by the IC engine using a waste heat recovery system that converts heat into mechanical energy with, for example, a Rankine cycle.
While these prior art attempts have improved the vehicle's efficiency, they lack adequate control of the working fluid and the working fluid's temperature. For example, U.S. Pat. No. 4,031,705 discloses a heat recovery system that heats the working fluid using heat from the IC engine's exhaust and the IC engine's cooling circuit, i.e., the IC engine's radiator. Therefore, while the '705 patent does utilize multiple heat sources, there is no way to adequately control where the heat is being drawn from. This can be problematic at times since insufficient flow of working fluid to a heat source can reduce the overall efficiency of the heat recovery system and/or result in wet steam being fed to the expander.
Waste heat recovery systems may use a working fluid to recover the waste heat from the engine. Some waste heat recovery system may use water. In such waste heat recovery systems, the water may be heated to steam using an evaporator. Other fluids, which may be non-aqueous, and which may include hydrocarbons such as ethanol or organofluorines such as Freon®, may also be used due to properties such as heat transfer, vapor pressure or freezing point (for example, a freezing point temperature lower than that of water). However such other fluids may combust when exposed to a hot metal surface such as an exhaust pipe on an engine or may be restricted by regulations when released to atmosphere. The fluids may also decompose when exposed to atmosphere. Such fluids may also be more prone to leaking past dynamic seals, i.e. seals that employ abutting surfaces that are configured to move relative to one another, due to, for example, lower fluid viscosity or limited lubrication for the dynamic seals.
Many waste heat recovery systems employ fluid control modules to control the flow of the working fluid through the waste heat recovery systems. For example, the fluid control modules may employ valves that regulate the working fluid flow to expanders in the waste heat recovery system. Such valves may utilize dynamic seals with working fluid on one side of the dynamic seal and atmosphere on the other side of the dynamic seal. These may be referred to as atmospheric dynamic seals. Sometimes the dynamic seals fail unexpectedly causing the working fluid to leak to atmosphere or onto a hot engine surface. Static seals may not be as prone to failure as dynamic seals.
Accordingly, there is a need for a static seal fluid control module for waste heat recovery systems. There is also a need for waste heat recovery systems with fluid and vapor control modules that do not have atmospheric dynamic seals.